Wireless telecommunications can be divided into two broad categories; mobile wireless communications and fixed wireless communications. Each category has its own unique market in terms of customer needs and technology requirements. Mobile wireless communications requires non-tethered communications and typically allows roaming, i.e., the ability to provide service to a mobile node while the mobile node is outside it's home system. On the other hand, fixed wireless communications simply provide an alternative to wired communications or an alternative system of providing service. A fixed wireless device does not need mobility. Instead, the fixed wireless device needs cost effective telecommunications from fixed locations.
The Internet offers access to information sources worldwide and the increasing variety of wireless devices and wireless systems offering Internet protocol (IP) connectivity, such as personal digital assistants (PDAs) and cellular telephones, increases the ability to access the Internet. Fixed points of attachment to the Internet, such as fixed wireless connections, do not offer the flexibility afforded by mobile points of attachments to the Internet. The IP routes data packets of information for fixed points of attachment to their destinations according to IP addresses that are associated with a fixed network location much as a non-mobile telephone number is associated with a physical jack in a wall.
Mobile points of attachment, referred to as “mobile computing and networking,” allow a user to change a wireless device's point of attachment to the Internet and not disrupt connectivity. Instead, a reconnection may occur essentially automatically and non-interactively. For example, in a wireless local area network (LAN) office environment, where the boundaries between attachment points are not sharp and are often invisible, a user may change points of attachment to the Internet substantially transparently. The mobile Internet protocol (Mobile IP) allows mobile nodes to transparently move between different IP networks and receive IP data packets accordingly. The mobile node is assigned to a particular network or home network and is also assigned a static IP address or home address associated with this home network. The mobile node may communicate with the home network through a device referred to as a “home agent.” The mobile node may move to another network or foreign network and register with the foreign network through a device referred to as a “foreign agent.” The foreign agent may assign a care-of address that is unique to that point of attachment.
In mobile IP, the home address is static and is used, for instance, to identify transmission control protocol (TCP) connections. The care-of address changes at each new point of attachment and can be thought of as the mobile node's topologically significant address. The care-of address identifies the mobile node's point of attachment with respect to the overall network topology.
The home address makes it appear that the mobile node is continually able to receive data on its home network through the home agent. Whenever the mobile node is not attached to its home network, the mobile node is attached to a foreign network and registered to a foreign agent. The mobile node may then communicate with its home network through the foreign network. Whenever the mobile node moves, it registers its new care-of address (i.e., point of attachment) with its home agent.
The home agent typically maintains a mobility binding record (MBR) for each mobile node. The MBR is used to keep track of mobile communications information such as a home address of the mobile node on the home network, a care-of address for the mobile node on a foreign network, and a lifetime timer for the association between the home address and the care-of address. Similarly, the foreign agent may maintain communication records of mobile nodes. For example, the foreign agent typically maintains records indicating assignment of care-of-addresses for visiting mobile nodes.
In addition, the foreign agent may have access to additional information that the home agent does not have access. This information may be useful for the home agent, especially if applications reside on the home network rather than the foreign network.